Janet Napolitano, the president of the University of California system and former U.S. Homeland Security secretary, publicly apologized Thursday for calling chants by students protesting tuition hikes "crap," a remark overheard on an open microphone at a board of regents meeting.

Napolitano, also a former Arizona governor, opened a regents meeting by expressing contrition, a day after the university's recording of a Wednesday gathering captured her saying, "We don't have to listen to this crap," when she leaned over to the board chairman who had just activated his microphone.

The comment came after several dozen students in the University of California system stripped off their shirts at Wednesday's meeting, tossed fake money in the air and stood on chairs chanting, "Egregious. Step off it. Put people over profits."

Students were protesting tuition increases of up to 5 percent in each of the next five years, what they say is a lack of support for black students at UC Berkeley, and concern that a possible new campus in Richmond would displace low-income residents.

Napolitano apologized Thursday "for using a word that she doesn't normally use, which was picked up on the mike, and suggested that many of us have been in similar situation where an inadvertent comment was overheard," Dianne Klein, spokeswoman for the University of California Office of the President, said in an email.

Klein said the time allotted for public comments had ended Wednesday when protesters interrupted.

"This went on for quite some time and when the participants ignored police instructions to end their protest, the board chair began following the established procedure to temporarily shut down the meeting," Klein said.

Napolitano's comment reflected her personal frustration with disruptions that hinder discussions on topics "vital to the future of the university and the education of its students," Klein said.